You have complete control over which items are shown in QuickPick. Instead of automatically showing you all of the applications or documents on your computer, QuickPick lets you pick and choose exactly which items you want to use.
To add items:
There are also other options for adding items into QuickPick. You can also drag and drop files onto the QuickPick icon in the Dock, and QuickPick will automatically add them to the current page.
To remove items:
When removing items from QuickPick, the items are only removed from QuickPick itself; they are not deleted from your system in any way.